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Jan. 3, 2008 -- Patients who respond quickly to hepatitis C (HCV) treatment may be able to safely stop therapy much sooner than is currently recommended, new research suggests.

Researchers in Italy report that cure rates were similar among HCV patients who had the recommended 48 weeks of treatment and those treated for half that time, as long as the patients had no evidence of HCV in their blood four weeks into treatment.

Hepatitis C can have different strains known as genotypes. The study included only patients with genotype 1. In a separate study involving genotype 2 and 3 patients, who tend to respond better to current treatments and have a shorter treatment course, response rates were similar among early viral responders whether they were treated with 12 weeks of treatment or the recommended 24 weeks.

The goal of HCV treatment is to achieve sustained virologic response. A sustained virologic response is defined as no detectable evidence of virus in the blood six months after finishing treatment.

Patients in both studies were treated with standard combination treatment including the long-acting version of the drug interferon and the antiviral drug ribavirin.

The studies are published in the January issue of the journal Hepatology.

Genotype and HCV Outcomes

About 3.2 million Americans have chronic HCV infection, and most of them have the more difficult-to-treat genotype 1.

Only about half of all patients with genotype 1 treated with peginterferon and ribavirin will achieve a sustained viral response, compared with 70% to 90% of patients with genotype 2 or genotype 3.

It is also increasingly clear that regardless of genotype, patients who respond early to treatment have the best chances for a cure.

With this in mind, the researchers in Italy enrolled just under 700 HCV genotype 1 patients in a study designed to compare outcomes among early responders treated for different durations.

A total of 26.6% were early-viral clearers, meaning that they achieved undetectable HCV levels by week four of treatment.

Among this subgroup of patients, 77% treated for a total of 24 weeks cleared the virus for good, compared with 87% treated for 48 weeks.

Patients who did not achieve viral responses until week 12 of treatment needed 72 weeks of therapy for a similar cure rate. When these patients received standard duration treatment of 48 weeks, just 38% achieved sustained viral responses.

"We found that approximately a quarter of HCV genotype 1 patients may be cured by therapy in only 24 weeks, and that a [comparable number] may require extended treatment to 72 weeks," the researchers wrote.

The Norway study involved 302 HCV patients with genotypes 2 and 3 who achieved early viral responses with treatment. Half the patients were treated for a total of 12 weeks and the other half received the standard HCV genotype 2 and genotype 3 course of 24 weeks.

In all, 81% of the patients in the shorter-treatment group achieved sustained viral responses, compared to 91% in the longer-treatment arm of the study.

Customizing HCV Treatment

Both studies suggest that customizing treatment length based on early therapeutic responses could improve patient cure rates.

University of North Carolina hepatitis C expert Michael W. Fried, MD, agrees, but he adds that more research is needed to better understand how to best tailor treatments based on patient responses.

He points out that response rates were slightly better among early responders treated for the recommended times in both studies.

Fried is a professor of medicine and director of hepatology at the University of North Carolina at Chapel Hill.

"Response rates were similar, but they were not identical," he says. "There was still about a 10% drop in sustained responses among patients treated for shorter periods."

Fried says the findings may have the biggest implications for patients who respond to treatment but have trouble staying on it.

"People who are not tolerating treatment well or who may be anxious to stop may be able to stop early without too much risk," he says.